Process of treating coal-gas for extracting tar, water, and ammonia.



UNITED STATES" PATENT OFFICE;

WALTHER FELD, OF HUNNINGEN-ON-THE-RHINE, GERMANY. I PROCESS OF TREATING COAL-GAS FOR EXTRACTING TAR, WATER, AND AMMONIA.

Specification of Letters Patent.

Patented Sept. 11, 1906;

Application filed January 4, 1906. Serial No. 294,668.

To all whom it may concern.-

altogether out of proportion to the value of nal amount of ammonia.

Be it known that I, WALTHER FELD, chemist and manufacturer, a subject of the King of Prussia, German Emperor, residing at Honningen-on-the-Rhine, in the Kingdom of Prussia, German Empire, have invented new and useful Improvements in the'Treatment of Coal-Gas and Analogous Gases for the Extraction of Ammonia Therefrom, of which the following is a specification.

Hitherto tar has been se arated from illuminating-gases and the like which contain tar, Water, and ammonia by cooling the gases to a low temperaturesay from-20 to 25 centigrades0 that the water in the gases is condensed at the same time as the tar. The objection to this method is, however, that the tar cannot be-completely separated from the gases by the cooling process alone and to separate the ammonia from the Water which is condensed in this cooling process requires the expense of handling a quantity of Water the ammonia contained therein, especially in view of the poor quality of the ammonia obtained. For this reason the recovery of ammonia from such gases is in many cases impracticable. These disadvantages are obviated by my invention.

I first completely separate the tar from the gases at such a temperature that no ammonia is absorbed by the tar. I then separate the water from the gases Without carrying away ammonia with this water. Having thus se arated the tar and water from the gases, the said gases still contain their origi- This I extract by means of acids or salt solutions and obtain the ammoniacal solutions undiluted by the water of the gases and not mixed with tarry matters and other impurities. I have found that this separation of tar and water can be effected by special treatment of the gases first with the tar which has been already separated from the gases and then with water separated from the gases, thistreatment being performed at a temperature above 40 centigrade. At this temperature most of the ammonia compounds present in the ases such as the carbonate, cyanid, and sulfi dare volatile or decomposed and only a small part of them can be formed and'dissolved in the tar and in the Water whichhave been separated from the gases. The higher therefore above'40 centigfade that the temperature of the gases is kept in separating the tar and treated water therefromthe less will be the amount ofammonia absorbed by the tar and condensed water. This separation of the tar maybe secured at a temperature even as high as 500 centigrade.

I may carry out my invention as follows: To separate the tar from the gases, the latter are'cooled to a temperature under 500 centigrade, (preferably, between and 200 centigra e, and at this temperature they are with a liquid which causes the tarto be condensed. The most suitable liquid for this operation is hotter already condensed and separated, but still in the separator, the said tar being dispersed in the form of fine spray across the space through which the gases to be treated pass. Nearly the whole of the taris thus separated-from the gases without condensing the water suspended in the gases. In order to remove the last traces of tarry matter from the latter, however,

they may be washed in a second apparatus at nearly the same temperature (under 500 and preferably between 100 and 200 centigrade) with tar-oil or thin tar or by an apparatus such as that known as the Pelouse apparatus. If the temperature of the gases passing the tar-washenwere lower than 100 centi rade, some water would be condensed; but t is would not absorb much ammonia so long as the temperature be kept above 40 centigrade. The gases thus freed from tar and .being in a warm and moist condition enter the water-condenser. The separation of the water may be effected in a way similar to that in which the separation of tar was effected, as aforesaid-namely, by treating the gases with a liquid which causes the water contained in the gases in the form of vapors or suspended spray to condense in the form of 'dro s. For this purpose the water condenser in effecting the separating of tar as aforesaid or in the cooler hereinafter referred to may be used, and this water may be warm or even hot. Preferably the water-condenser is so constructed that the water introduced into and that condensed in th condenser before leaving it is spread in tie form of fine spray across the space through which the gases pass. If the gases contain fixed ammomacompounds, milk of lime is runinto" monia compounds, steam can be blown .into

tageous to conduct the process in such a way that the gases entering the condenser have a temperature from 90 to 150 centigrade or even a higher temperature, in which case the condensed water leaves the condenser so hot that no steam is necessary to decompose the ammonia compounds in the water, thus keeping the water free from ammonia.

The following is an example of how the separation of water is effected. If cokeworks coal containing twelve per cent. of water be distilled and if from this coal three hundred cubic meters of gases be produced per ton of such coal, the said gasescontain one hundred and twenty kilograms of water,

per three hundred cubic meters of gases or four' hundred grams of water per cubic meter of the gases. If the gasesenter the water-condenser at 120 centigrade and leave it at centigrade, the gases, according to their capacity of saturation with water-vapors at 65 centigrade, leave the condenser still containing one hundred and sixty grams of water per cubic meter, two hundred and forty grams of water being condensed in the condenser. The ases coming from the condenser are 000 ed in the cooler from 65 to 40 centigrade and leave the cooler, according to their. capacity of saturation, at 40 centigrade with fifty grams of, waterper cubic meter, one hundred andtenigramsof water at 40 centigrade being condensed in the cooler. This water' at 40 centigrade, separated in the cooler, is run into the Water-condenser and is spread therein in the form of fine spray, and by passing through the condenser the water is. heated from 40 to betweenand centigrade and gives off its ammonia to the gases, the gases on their way through the condenser givin off their heat to the water run in and being cooled from -to 65 ,centigrade. The gases, which may come-from the cooler at 40 centigrade, are treated with a solution of a salt of an alkali, an earth alkali, magnesia, or the like, giving off ammonia and carbonic acid to the solutions in forming corresponding ammonia salts. For example, in washing with chlorid of magnesia the following reaction occurs:

If the salt solution be run into tl e ammonia washer at 40 centigradethati%7to say\ at the temperature of the gases to be 'aslied -no moisture from the gas will be condensed in the salt solution, and this will not be diluted.

In working according to my invention, as

hereinbefore described, the separation of tar will be complete, and the tar being free from water andaammonia will be more valuable than hitherto. The recovery of ammonia will be complete also, the ammonia being extracted uniformly and in the form of a liquor which is more concentrated and purer and more valuable than hitherto.

Having now particularly described and ascertained the nature of iny said invention and the manner in whichthe same is to be performed, I declare that what I claim is 1. 'A process for the extraction of tar and ammonia from gases containing tar, water and ammonia, consisting in first separating tar and then the water of distillatlon from the said gases, by treating the said gases at a temperature above 40 and under'500 centigrade with liquid capable of causing the tar and water respectively to take the form of drops and of precipitating these drops and, after thus separating tar and water, treating the said gases with an agent which Will ex-' tract the ammonia fronl the said gases.

'2. A process for the extraction of tar and ammonia from gases containing tar, water and ammonia, consisting in first separating from the said gases, tar at a temperature of from 100 to 200 .centigrade and afterward separating, from the said gases, the water of distillation at a temperatureabove 40 and then treating the said gases with an agent which will extract the ammonia from the said gases. I

, 3. A process for the extraction of tar and ammonia from gases containing tar, water and ammonia, consisting in effecting the sep aration of tar bytreating the said gases, at a temperature above 40 centigradeand under 500 centigrade, with tar already separated from like gases, and spread, before it leaves the tar-separator, in the form of a fine spray across the space through which the gases to be treated pass, and then separating the water of distillation at a temperature above 40 centigrade and under 500 centigrade, and then treating the said gases with an agent which will extract the ammonia fromthe said ases.

g 4. A process for the extraction of tar and ammonia from gases containing tar, water and ammonia, consisting in first separatingv tar at a temperature above 40 centigrade and under 500-centigrade, and then separating water of distillation bytreating the said gases at a temperature of from 90 to to a further cooling process, treating the said gases with an agent which will extract the ammonia from the said gases.

5. A process for the extraction of tar and ammonia from gases containing tar, water and ammonia, cons st ng in firstseparating tar at a temperature above centigrade and under 500 centigrade, and then separating water of distillation by treating the gases 6. A process for the extraction of tar and ammonia from gases containing tar, water and ammonia, consisting in the -separation of tar from gases by assing the gases through a spray of liqui tar at a. temperature of from to 500 centigrade, so that the tar is obtained free, or practically free, from water and ammonia.

7. A process for the extraction of tar and ammonia from gases, containing tar, Water and ammonia, consisting in the separation of water from gases by passing the gases (after the removal of the tar) through a spray of water at a temperature above 40 and under centigrade so that the water is separated without absorbing the ammonia and subsequently removing the ammonia from the gases.

8. A process for the extraction of tar and ammonia from gases, containing tar, water and ammonia and consisting in the obtainment from gases, of tar free, or practically free, from Water and ammonia, and the subsequent obtainment of ammonia, by first passing the gases through a spray of liquid tar at a temperature of 100 to 500 centi' grade and then through a s ray of water at a temperature above 40 an under 120 centigrade and afterward absorbing the ammonia from the gases from which the tar and water have been separated.

In testimony whereof I have signed this specification in'the presence of two subscribing witnesses.

WALTHER FELD. Witnesses:

BESSIE F. DUNLAP, LoUIs VANDoRY. 

